* {
    margin: 0;
    padding: 0;
}
body {
    display: flex;
    /* 在主轴上居中 */
    justify-content: center;
    /* 在交叉轴上居中 */
    align-items: center;
    height: 100vh;
    background-color: #000;
}
ul {
    /* 相对定位 */
    position: relative;
    display: flex;
    height: 200px;
}
ul::after {
    content: "爱心";
    position: absolute;
    top: -120px;
    left: 48%;
    color: darkturquoise;
    font-size: 30px;
    font-weight: 700;
    /* 垂直居中 */
    transform: translatey(-50%);
}
li {
    width: 20px;
    height: 20px;
    border-radius: 10px;
    margin: 0 10px;
}
li:nth-child(1) {
    background-color: red;
    /* 5秒完成动画不延迟 */
    animation: love1 5s 0s infinite;
}
li:nth-child(2) {
    background-color: darkturquoise;
    animation: love2 5s 0.2s infinite;
}
li:nth-child(3) {
    background-color: darksalmon;
    animation: love3 5s 0.4s infinite;
}
li:nth-child(4) {
    background-color: deeppink;
    animation: love4 5s 0.6s infinite;
}
li:nth-child(5) {
    background-color: yellow;
    animation: love5 5s 0.8s infinite;
}
li:nth-child(6) {
    background-color: deeppink;
    animation: love4 5s 1s infinite;
}
li:nth-child(7) {
    background-color: darksalmon;
    animation: love3 5s 1.2s infinite;
}
li:nth-child(8) {
    background-color: darkturquoise;
    animation: love2 5s 1.4s infinite;
}
li:nth-child(9) {
    background-color: red;
    animation: love1 5s 1.6s infinite;
}
/* 定义动画 */
@keyframes love1 {
    30%,50% {
        height: 60px;
        transform: translatey(-30px);
    }
    70%,100% {
        height: 20px;
        transform: translatey(0);
    }
}
@keyframes love2 {
    30%,50% {
        height: 125px;
        transform: translatey(-60px);
    }
    70%,100% {
        height: 20px;
        transform: translatey(0);
    }
}
@keyframes love3 {
    30%,50% {
        height: 160px;
        transform: translatey(-75px);
    }
    70%,100% {
        height: 20px;
        transform: translatey(0);
    }
}
@keyframes love4 {
    30%,50% {
        height: 180px;
        transform: translatey(-60px);
    }
    70%,100% {
        height: 20px;
        transform: translatey(0);
    }
}
@keyframes love5 {
    30%,50% {
        height: 200px;
        transform: translatey(-45px);
    }
    70%,100% {
        height: 20px;
        transform: translatey(0);
    }
}
